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Re: [PLUG] Ubuntu Alternate installer, RAID1 & LVM
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On May 16, 2008, at 8:03 AM, Matt Mossholder wrote:
> On Fri, 2008-05-16 at 07:53 -0400, Matt Mossholder wrote:
>> If not, you could always have LVM do the mirroring on /boot, rather
>> than
>> use md.
>
> Please ignore this.. while LVM does support striping, it doesn't
> support
> mirroring. Rather odd, eh?
I wouldn't say it's odd.. LVM is aimed at solving partitioning
issues, while RAID is aimed at solving redundancy issues.
The "striping" in LVM is really JBOD, while a proper RAID setup would
use identical sized volumes to build the redundant volume.
It makes lots of sense to actually combine the two even.
So, you stick 2 drives in a server, and put them together in RAID-1
as /dev/md0. Everything's cool, until you decide, "Hey, I really
could use more space on /home". Since you just put the filesystem
directly on the raid device, you're stuck, unless you add drives, and
shuffle lots of stuff around.
Instead, you designate /dev/md0 as a physical volume for LVM, then
carve out LVM slices for your partitions. Need to add space to /home?
No problem. Add another couple of drives, put them together as
RAID-1, add them to the LVM volume group and expand the /home
filesystem...
--j
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